Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments - Additional Information (Detail)

v3.21.2
Financial Instruments - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Jul. 31, 2021
Jul. 31, 2020
Apr. 30, 2021
Financial Instrument [Line Items]      
Sale/maturities of available-for-sale marketable securities $ 21.7 $ 11.8  
Unrealized gains relates to equity securities 4.1 11.4  
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts      
Financial Instrument [Line Items]      
Foreign currency gains (losses) 0.1 $ 0.8  
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Purchased      
Financial Instrument [Line Items]      
Derivative notional amount 79.7   $ 69.4
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Sold      
Financial Instrument [Line Items]      
Derivative notional amount $ 45.4   $ 44.9
Available-for-sale Marketable Securities | Minimum      
Financial Instrument [Line Items]      
Marketable securities remaining maturity 1 month    
Available-for-sale Marketable Securities | Maximum      
Financial Instrument [Line Items]      
Marketable securities remaining maturity 22 months